Thermosetting resin composition, method for producing resin composition varnish, prepreg and laminate

ABSTRACT

Discloses are a thermosetting resin composition containing a maleimide compound including an unsaturated maleimide compound having a specified chemical structure, a thermosetting resin, an inorganic filler, and a molybdenum compound; a laminate plate for wiring boards obtained by coating a base material with a thermosetting resin composition containing a thermosetting resin, silica, and a specified molybdenum compound and then performing semi-curing to form a prepreg, and laminating and molding the prepreg; and a method for manufacturing a resin composition varnish including specified steps. According to the present invention, electronic components having low thermal expansion properties and excellent drilling processability and heat resistance, for example, a prepreg, a laminate plate, an interposer, etc., can be provided.

TECHNICAL FIELD

The present invention relates to a thermosetting resin composition whichis especially low in thermal expansion properties and excellent indrilling processability and heat resistance and which is suitably usedfor electronic components, etc.; a prepreg and a laminate plate eachusing the same; a laminate plate for wiring boards requiring a drillingprocessing treatment at a manufacturing stage for wiring board; amanufacturing method of a resin composition varnish; and a prepreg and alaminate plate fabricated utilizing the subject manufacturing method,each of which is suitable for semiconductor packages and printed wiringboards.

BACKGROUND ART

In a wiring board to be used for semiconductor packages (hereinafterreferred to as “interposer”), it is general to perform a large number ofdrilling processing for interlayer connection of wirings. Inconsequence, a laminate plate for interposers is required to have highdrilling processability.

Now, for a laminate plate for semiconductor packages, there havehitherto been used a lot of curable resin compositions composed of abismaleimide compound and a cyanate resin (for example, Patent Document1). This is because in view of the fact that the subject resincompositions are excellent in heat resistance, the resin compositionswere suitable as a resin composition for the laminate plate forsemiconductor packages, which is frequently exposed to high temperaturesin a reflow step or the like at the time of mounting.

However, in recent years, requirements for thinning and weight reductionof electronic appliances are increased, and associated with rapidprogress of thinning and high density of semiconductor packages,laminate plates for semiconductor packages have also been required tohave higher characteristics other than heat resistance over broadregions.

Above all, in order to suppress an increase of a warp at the time ofmounting to be caused due to thinning of a semiconductor package, it isstrongly required to make a coefficient of thermal expansion of alaminate plate for semiconductor packages close to that of a siliconchip, namely to realize low thermal expansion.

While there are considered a variety of techniques for realizing lowthermal expansion of the laminate plate, it is effective to allow aresin per se for laminate plates to realize low thermal expansion, or tofill an inorganic filler in a high density in a resin composition. Forthat reason, a novolak type cyanate resin is used, or a content of theinorganic filler is increased (for example, Patent Document 2).

But, the use of a cyanate resin or the filling of an inorganic filler ina high density involved such a problem that cutting properties of theresin composition are lowered, thereby significantly impairing drillingprocessability of a laminate plate using such a resin composition.

Then, there was made an attempt to prevent a lowering of the drillingprocessability by adding a plate-shaped filler such as burnt talc, etc.as an inorganic filler or reducing a content the inorganic filler (forexample, Patent Document 3). However, there were such inconveniencesthat the effect for preventing a lowering of the drilling processabilityis insufficient; the resin composition becomes low in elasticity, sothat the effect for suppressing a warp of the semiconductor package isinsufficient; and so on. Thus, satisfactory results have not beenobtained yet.

In order to realize low thermal expansion of the laminate plate, it iseffective to increase a content of a filler having a small coefficientof thermal expansion, such as silica, among inorganic fillers in theresin composition used in the laminate plate. But, if the content of ahard filler such as silica is increased, there was encountered such aproblem that the drilling processability of the laminate plate islowered.

Also, in order to enhance the drilling processability, there is made anattempt to add a metal dichalcogenide such as molybdenum disulfide as aninorganic solid lubricant particle (see, for example, Patent Document4). But, if molybdenum disulfide is added, there is encountered such aproblem that electrical insulating properties of the laminate plate aresignificantly lowered. Thus, satisfactory results have not been obtainedyet.

Then, in order to solve this problem, the present inventors investigatedadditives which even when an inorganic filler is filled in high density,can inhibit the deterioration of the drilling processability and thenfound that a molybdenum compound has an excellent effect.

But, since the molybdenum compound has a large specific gravity, whenadded directly to a resin composition varnish to be used for thefabrication of a laminate plate, it easily precipitates to causedefective manufacture. For that reason, it is recommended to use aparticle having a molybdenum compound supported on talc or the like (forexample, KEMIGARD 911C, manufactured by Sherwin-Williams Company) (see,for example, Patent Document 5). However, there are such drawbacks thatthe resin composition varnish is thickened; aggregation of themolybdenum compound-supported particles with each other easily occurs;and so on. Thus, satisfactory results are not obtained.

PRIOR ART DOCUMENTS Patent Documents

Patent Document 1: JP-A-3-52773

Patent Document 2: Japanese Patent No. 4132703

Patent Document 3: JP-A-2005-162787

Patent Document 4: JP-T-2002-527538

Patent Document 5: JP-A-2000-264986

DISCLOSURE OF THE INVENTION

Under such circumstances, the present invention has been made. A firstobject of the present invention is to provide a thermoplastic resincomposition which is especially low in thermal expansion properties andexcellent in drilling processability and heat resistance and which issuitably used for electronic components, etc., and a prepreg and alaminate plate each using the same; and a second object thereof is toprovide a laminate plate for wiring boards, which is very excellent indrilling processability at the time of fabricating a wiring board andwhich also has favorable electrical insulating properties and lowthermal expansion properties.

Furthermore, a third object of the present invention is to provide amethod for manufacturing a resin composition varnish, in whichprecipitation or aggregation of a molybdenum compound hardly occurs, anda prepreg and a laminate plate each having a low coefficient of thermalexpansion and high drilling processability.

The present inventors made extensive and intensive investigations. As aresult, it has been found that the foregoing first object can beachieved by a thermosetting resin composition containing an unsaturatedmaleimide compound having an acidic substituent composed of a specifiedchemical formula, a thermosetting resin, an inorganic filler, and amolybdenum compound; the foregoing second object can be achieved byforming a laminate plate by using a thermosetting resin compositioncontaining a thermosetting resin, a specified amount of silica, and aspecified molybdenum compound; and furthermore, the foregoing thirdobject can be achieved by manufacturing a resin composition varnish by amethod in which after a molybdenum compound is dispersed and mixed in aslurry having a specified silica particle dispersed therein, this slurryis added to a varnish containing a thermosetting resin, and thereafter,an inorganic filler is blended therewith. The present invention has beenaccomplished on the basis of such knowledge.

That is, the present invention provides the following.

(1) A thermosetting resin composition comprising (A) a maleimidecompound containing an unsaturated maleimide compound having an acidicsubstituent, as represented by the following general formula (I) or(II), (B) a thermosetting resin, (C) an inorganic filler, and (D) amolybdenum compound:

(In the formulae, R₁ represents a hydroxyl group, a carboxyl group, or asulfonic acid group, each of which is the acidic substituent; each ofR₂, R₃, R₄, and R₅ independently represents a hydrogen atom, analiphatic hydrocarbon group having a carbon number of from 1 to 5, or ahalogen atom; A represents an alkylene group, an alkylidene group, anether group, a sulfonyl group, or a group represented by the followingformula (III); x represents an integer of from 1 to 5; y represents aninteger of from 0 to 4; and a sum of x and y is 5.)

(2) The thermosetting resin composition as set forth above in (1),wherein the molybdenum compound (D) is at least one member selected froma molybdenum oxide and a molybdic acid compound, and a content of themolybdenum compound is from 0.02 to 20% by volume of the whole of theresin composition.(3) The thermosetting resin composition as set forth above in (1) or(2), wherein the thermosetting resin (B) is an epoxy resin; a total sumcontent of the component (A) and the component (B) is from 30 to 80% byvolume of the whole of the resin composition; and a mass ratio of thecomponent (A) and the component (B) is from 20 to 90 parts by mass interms of the component (A) based on 100 parts by mass of the total sumcontent of the component (A) and the component (B).(4) The thermosetting resin composition as set forth above in any one of(1) to (3), wherein the inorganic filler (C) is fused spherical silica,and a content of the inorganic filler is from 10 to 60% by volume of thewhole of the resin composition.(5) A prepreg obtained by impregnating or coating a base material withthe thermosetting resin composition as set forth above in any one of (1)to (4) and then performing B-staging.(6) A laminate plate obtained by laminating and molding the prepreg asset forth above in (5).(7) The laminate plate as set forth above in (6), which is a metal cladlaminate plate obtained by superimposing a metal foil on at least onesurface of the prepreg and then performing heat pressure molding.(8) A laminate plate for wiring boards, obtained by coating athermosetting resin composition containing (E) a thermosetting resin,(F) silica, and (G) at least one molybdenum compound selected from zincmolybdate, calcium molybdate, and magnesium molybdate, with a content ofthe silica (F) being 20% by volume or more and not more than 60% byvolume, on a base material in a film form or fiber form, then performingsemi-curing to form a prepreg, and laminating and molding the prepreg.(9) The laminate plate for wiring boards as set forth above in (8),wherein the silica (F) is fused spherical silica having an averageparticle size of 0.1 μm or more and not more than 1 μm, and a content ofthe molybdenum compound (G) is from 0.1% by volume or more and not morethan 10% by volume of the whole of the resin composition.(10) The laminate plate for wiring boards as set forth above in (8) or(9), wherein the thermosetting resin composition is varnished.(11) The laminate plate for wiring boards as set forth above in any oneof (8) to (10), wherein the base material in a film form or fiber formis a glass cloth.(12) A method for manufacturing a resin composition varnish comprising

a first dispersing and mixing step of dispersing and mixing (I) amolybdenum compound in (H) a slurry containing a silica particle havingan average particle size of 0.01 μm or more and not more than 0.1 μm anda specific surface area of 30 m²/g or more and not more than 270 m²/g,

a second dispersing and mixing step of dispersing and mixing the slurryhaving gone through the first dispersing and mixing step in a varnishcontaining (J) a thermosetting resin, and

a third dispersing and mixing step of dispersing and mixing (K) aninorganic filler exclusive of the silica particle and the molybdenumcompound in the varnish having gone through the second dispersing andmixing step.

(13) The method for manufacturing a resin composition varnish as setforth above in (12), further comprising a curing accelerator adding stepof adding a curing accelerator to the varnish after the third dispersingand mixing step.(14) The method for manufacturing a resin composition varnish as setforth above in (12) or (13), wherein the molybdenum compound (I) is onemember or a mixture of two or more members selected from the groupconsisting of zinc molybdate, calcium molybdate, and magnesiummolybdate.(15) A prepreg comprising a base material impregnated and coated with aresin composition varnish obtained through a first dispersing and mixingstep of dispersing and mixing (I) a molybdenum compound in (H) a slurrycontaining a silica particle having an average particle size of 0.01 μmor more and not more than 0.1 μm and a specific surface area of 30 m²/gor more and not more than 270 m²/g; a second dispersing and mixing stepof dispersing and mixing the slurry having gone through the firstdispersing and mixing step in a varnish containing (J) a thermosettingresin; and a third dispersing and mixing step of dispersing and mixing(K) an inorganic filler in the varnish having gone through the seconddispersing and mixing step.(16) A laminate plate obtained by laminating and molding the prepreg asset forth above in (15).

The thermosetting resin composition of the present invention isespecially low in thermal expansion properties and excellent in drillingprocessability and heat resistance and is suitably used for electroniccomponents, etc.

For that reason, according to the present invention, a prepreg and alaminate plate each having an excellent performance, and so on can beprovided by using the subject thermosetting resin composition.

Also, according to the present invention, a laminate plate for wiringboards, which is very excellent in drilling processability at the timeof fabricating a wiring board and which also has favorable electricalinsulating properties and low thermal expansion properties, can beprovided. In consequence, when an interposer is manufactured by usingthe laminate plate for wiring boards of the present invention, asemi-conductor package which is less in a warp at low costs can beobtained.

Furthermore, according to the present invention, a method formanufacturing a resin composition varnish, in which precipitation oraggregation of a molybdenum compound hardly occurs, and a prepreg and alaminate plate each having a low coefficient of thermal expansion andhigh drilling processability can be provided.

MODES FOR CARRYING OUT THE INVENTION

First of all, the thermosetting resin composition of the presentinvention is described.

[Thermosetting Resin Composition]

The thermosetting resin composition of the present invention is a resincomposition containing, as essential components, (A) a maleimidecompound containing an unsaturated maleimide compound having an acidicsubstituent, as represented by the following general formula (I) or(II), (B) a thermosetting resin, (C) an inorganic filler, and (D) amolybdenum compound.

In the formulae, R₁ represents a hydroxyl group, a carboxyl group, or asulfonic acid group, each of which is the acidic substituent; each ofR₂, R₃, R₄, and R₅ independently represents a hydrogen atom, analiphatic hydrocarbon group having a carbon number of from 1 to 5, or ahalogen atom, R₂ to R₅ may be the same as or different from each other;A represents an alkylene group, an alkylidene group, an ether group, asulfonyl group, or a group represented by the following formula (III); xrepresents an integer of from 1 to 5; y represents an integer of from 0to 4; and a sum of x and y is 5.

First of all, the unsaturated maleimide compound having an acidicsubstituent, as represented by the general formula (I) or (II), which isthe component (A), can be, for example, manufactured by allowing amaleimide compound having at least two N-substituted maleimide groups inone molecule thereof and an amine compound having an acidic substituentrepresented by the following general formula (IV) to react with eachother in an organic solvent.

In the formula, each R₁ independently represents a hydroxyl group, acarboxyl group, or a sulfonic acid group, which is the acidicsubstituent; each R₂ independently represents a hydrogen atom, analiphatic hydrocarbon group having a carbon number of from 1 to 5, or ahalogen atom; x represents an integer of from 1 to 5; y represents aninteger of from 0 to 4; and a sum of x and y is 5.

Examples of the maleimide compound having at least two N-substitutedmaleimide groups in one molecule thereof includebis(4-maleimidophenyl)methane, bis(4-maleimidophenyl)ether,bis(4-maleimidophenyl)sulfone,3,3-dimethyl-5,5-diethyl-4,4-diphenylmethane bismaleimide,4-methyl-1,3-phenylene bismaleimide, m-phenylene bismaleimide,2,2-bis-(4-(4-maleimidophenoxy)phenyl)propane, and so on.

Of these, bis(4-maleimidophenyl)methane, m-phenylene bismaleimide, andbis(4-maleimidophenyl)sulfone are preferable because these compoundshave high reactivity and are able to realize higher heat resistance;m-phenylene bismaleimide and bis(4-maleimidophenyl)methane are morepreferable from the standpoint of inexpensiveness; andbis(4-maleimidephenyl)methane is especially preferable from thestandpoint of solubility in a solvent.

Examples of the amine compound having an acidic substituent representedby the general formula (IV) include m-aminophenol, p-aminophenol,o-aminophenol, p-aminobenzoic acid, m-aminobenzoic acid, o-aminobenzoicacid, o-aminobenzenesulfonic acid, m-aminobenzenesulfonic acid,p-aminobenzenesulfonic acid, 3,5-dihydroxyaniline, 3,5-dicarboxyaniline,and so on. Of these, m-aminophenol, p-aminophenol, p-aminobenzoic acid,m-aminobenzoic acid, and 3,5-dihydroxyaniline are preferable from thestandpoints of solubility and synthetic yield; and m-aminophenol andp-aminophenol are more preferable from the standpoint of heatresistance.

Though the organic solvent which is used for this reaction is notparticularly limited, examples thereof include an alcohol based solventsuch as ethanol, propanol, butanol, methyl cellosolve, butyl cellosolve,propylene glycol monomethyl ether, etc.; a ketone based solvent such asacetone, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone,etc.; an ether based solvent such as tetrahydrofuran, etc.; an aromaticsolvent such as toluene, xylene, mesitylene, etc.; a nitrogenatom-containing solvent such as dimethylformamide, dimethylacetamide,N-methylpyrrolidone, etc.; a sulfur atom-containing solvent such asdimethyl sulfoxide, etc.; and so on. These can be used singly or inadmixture of two or more kinds thereof.

Of these organic solvents, cyclohexanone, propylene glycol monomethylether, and methyl cellosolve are preferable from the standpoint ofsolubility; cyclohexanone and propylene glycol monomethyl ether are morepreferable from the standpoint of low toxicity; and propylene glycolmonomethyl ether is especially preferable in view of the fact that it ishigh in the volatility and hardly remains as a residual solvent at thetime of manufacturing a prepreg.

A use amount of the organic solvent is preferably from 10 to 1,000 partsby mass, more preferably from 100 to 500 parts by mass, and especiallypreferably from 200 to 500 parts by mass based on 100 parts by mass of atotal sum of the maleimide compound having at least two N-substitutedmaleimide groups in one molecule thereof and the amine compound havingan acidic substituent represented by the general formula (IV).

When the use amount of the organic solvent is 10 parts by mass or more,the solubility is sufficient, whereas when it is not more than 1,000parts by mass, the reaction time is not excessively long.

As for use amounts of the maleimide compound having at least twoN-substituted maleimide groups in one molecule thereof and the aminecompound having an acidic substituent represented by the general formula(IV), an equivalent ratio of a maleimide group equivalent of themaleimide compound and an equivalent of the amine compound as reducedinto an —NH₂ group is preferably in the range represented by thefollowing expression.

1.0<(Maleimide group equivalent)/(Equivalent as reduced into an —NH₂group)≦10.0

The subject equivalent ratio is more preferably in the range of from 2.0to 10.0. By allowing the subject equivalent ratio to fall within theforegoing range, the solubility in a solvent does not becomeinsufficient, the gelation is not caused, and the heat resistance of thethermosetting resin is not lowered.

Also, preferably, a reaction temperature is in the range of from 50 to200° C., and a reaction time is in the range of from 0.1 to 10 hours;and more preferably, the reaction temperature is in the range of from100 to 160° C., and the reaction time is in the range of from 1 to 8hours.

Incidentally, a reaction accelerator can be used in this reaction, asthe need arises. Examples of the reaction accelerator include an aminesuch as triethylamine, pyridine, tributylamine, etc.; an imidazole suchas methyl imidazole, phenyl imidazole, etc.; and an organic phosphorusbased compound such as triphenyl phosphine, etc. These can be usedsingly or in admixture of two or more kinds thereof.

By allowing the thermosetting resin composition of the present inventionto contain the unsaturated maleimide compound having an acidicsubstituent represented by the foregoing general formula (I) or (II) asthe component (A), low thermal expansion properties and excellent heatresistance are revealed. Though the component (A) may contain othermaleimide compound, it is preferable that the component (A) contains 60%by mass or more of the unsaturated maleimide compound having an acidicsubstituent represented by the general formula (I) or (II).

Examples of the thermosetting resin as the component (B) include anepoxy resin, a phenol resin, an unsaturated imide resin, a cyanateresin, an isocyanate resin, a benzoxazine resin, an oxetane resin, anamino resin, an unsaturated polyester resin, an allyl resin, adicyclopentadiene resin, a silicone resin, a triazine resin, a melamineresin, and so on. These can be used singly or in admixture of two ormore kinds thereof.

Of these, an epoxy resin is preferable from the standpoints ofmoldability and electrical insulating properties. Examples of such anepoxy resin include a bisphenol A type epoxy resin, a bisphenol F typeepoxy resin, a bisphenol S type epoxy resin, a phenol novolak type epoxyresin, a cresol novolak type epoxy resin, a bisphenol A novolak typeepoxy resin, a bisphenol F novolak type epoxy resin, a biphenyl typeepoxy resin, a xylylene type epoxy resin, a biphenyl aralkyl type epoxyresin, a naphthalene type epoxy resin, a dicyclopentadiene type epoxyresin, an alicyclic epoxy resin, a diglycidyl ether compound of apolyfunctional phenol or a polycyclic aromatic compound such asanthracene, etc., and so on. These can be used singly or in admixture oftwo or more kinds thereof.

In the case of using an epoxy resin as the thermosetting resin, a curingagent or a curing accelerator of the epoxy resin can be used, as theneed arises. Examples of the curing agent include a polyfunctionalphenol compound such as phenol novolak, cresol novolak, etc.; an aminecompound such as dicyandiamide, diaminodiphenylmethane,diaminodiphenylsulfone, etc.; an acid anhydride such as phthalicanhydride, pyromellitic anhydride, maleic anhydride, a maleic anhydridecopolymer, etc.; and so on. These can be used singly or in admixture oftwo or more kinds thereof.

Also, examples of the curing accelerator include an imidazole and aderivative thereof, an organic phosphorus based compound, a secondaryamine, a tertiary amine, a quaternary ammonium salt, and so on. Thesecan be used singly or in admixture of two or more kinds thereof.

As for contents of the component (A) and the component (B), a total sumcontent of the component (A) and the component (B) is preferably from 30to 80% by volume, and more preferably from 40 to 70% by volume of thewhole of the resin composition. By allowing the total sum content of thecomponent (A) and the component (B) to fall within the range of from 30to 80% by volume, the moldability and low thermal expansion propertiesof the resin composition can be kept favorable.

Also, a mass ratio of the component (A) and the component (B) ispreferably from 20 to 90 parts by mass, and more preferably from 30 to80 parts by mass in terms of the component (A) based on 100 parts bymass of the total sum content of the component (A) and the component(B). By allowing the content of the component (A) to fall within therange of from 20 to 90 parts by mass, the incombustibility, adhesion,and heat resistance of the resin composition can be kept favorable.

Examples of the inorganic filler as the component (C) include silica,alumina, talc, mica, kaolin, aluminum hydroxide, magnesium hydroxide,zinc borate, zinc stannate, zinc oxide, titanium oxide, boron nitride,calcium carbonate, barium sulfate, aluminum borate, potassium titanate,a glass powder of E-glass, S-glass, D-glass, etc., a hollow glass bead,and so on. These can be used singly or in admixture of two or more kindsthereof.

Of these, silica is preferable from the standpoint of low thermalexpansion properties. Examples of the silica include precipitated silicawhich is manufactured by a wet process and which has a high watercontent; and dry process silica which is manufactured by a dry processand which does not substantially contain bonding water, etc.Furthermore, the dry process silica includes crushed silica, fumedsilica, and fused spherical silica depending upon a difference of themanufacturing method. Of these, from the standpoints of low thermalexpansion properties and high fluidity upon being filled in the resin,fused spherical silica is preferable.

In the case of using fused spherical silica as the inorganic filler asthe component (C), its average particle size is preferably from 0.1 to10 μm, and more preferably from 0.3 to 8 μm.

When the average particle size of the fused spherical silica iscontrolled to 0.1 μm or more, the fluidity at the time of filling thefused spherical silica in a high density in the resin composition can bekept favorable, whereas when it is controlled to not more than 10 μm, aprobability of incorporation of coarse particles is reduced, therebyenabling one to suppress the generation of failure to be caused due tothe coarse particles.

When a cumulative distribution curve by particle size is determinedwhile defining the whole volume of the particles as 100%, the averageparticle size as referred to herein means a particle size correspondingto just 50% of the volume, and it can be measured by a particle sizedistribution analyzer adopting a laser diffraction scattering method, orthe like.

A content of the inorganic filler as the component (C) is preferablyfrom 10 to 60% by volume, and more preferably from 20 to 50% by volumeof the whole of the resin composition. By allowing the content of theinorganic filler to fall within the range of from 10 to 60% by volume ofthe whole of the resin composition, the moldability and low thermalexpansion properties of the resin composition can be kept favorable.

Examples of the molybdenum compound as the component (D) include amolybdenum oxide and a molybdic acid compound such as molybdenumtrioxide, zinc molybdate, ammonium molybdate, magnesium molybdate,calcium molybdate, barium molybdate, sodium molybdate, potassiummolybdate, phosphomolybdic acid, ammonium phosphomolybdate, sodiumphosphomolybdate, silicomolybdic acid, etc.; and an inorganic molybdenumcompound such as molybdenum boride, molybdenum disilicate, molybdenumnitride, molybdenum carbide, etc. These can be used singly or inadmixture of two or more kinds thereof.

Of these, a molybdenum oxide and a molybdic acid compound are preferablefrom the standpoint that the effect for preventing a lowering of thedrilling processability is favorable; and furthermore, zinc molybdate,calcium molybdate, and magnesium molybdate are especially preferablefrom the standpoints of low water solubility and toxicity and highelectrical insulating properties.

In the case where zinc molybdate, calcium molybdate, or magnesiummolybdate is used as the component (D), by supporting such a molybdenumcompound on talc, silica, zinc oxide, calcium carbonate, magnesiumhydroxide, or the like and using it, it is possible to contrive toprevent precipitation and enhance dispersibility at the time ofdissolving the resin composition in an organic solvent to form avarnish. Examples of such a molybdenum compound include KEMGARD 911C,manufactured by Sherwin-Williams Company, which is one having zincmolybdate supported on talc.

A content of the molybdenum compound as the component (D) is preferablyfrom 0.02 to 20% by volume, and more preferably from 0.1 to 15% byvolume of the whole of the resin composition. By allowing the content ofthe molybdenum compound to fall within the range of from 0.02 to 20% byvolume of the whole of the resin composition, not only the adhesion ofthe resin composition can be kept favorable, but the effect forpreventing a lowering of the drilling processability can be sufficientlyobtained.

Furthermore, the thermosetting resin composition of the presentinvention can arbitrarily contain known thermoplastic resin, elastomer,organic filler, flame retarder, ultraviolet ray absorber, antioxidant,and adhesion enhancer, and the like to an extent such that thermosettingproperties as the resin composition are not impaired.

Examples of the thermoplastic resin include polyethylene, polypropylene,polystyrene, a polyphenylene ether resin, a phenoxy resin, apolycarbonate resin, a polyester resin, a polyamide resin, apolyamide-imide resin, a polyimide resin, a xylene resin, apolyphenylene sulfide resin, a polyether imide resin, apolyetheretherketone resin, a polyether imide resin, a silicone resin, atetrafluoroethylene resin, and so on.

Examples of the elastomer include polybutadiene, polyacrylonitrile,epoxy-modified polybutadiene, maleic anhydride-modified polybutadiene,phenol-modified polybutadiene, carboxy-modified polyacrylonitrile, andso on.

Examples of the organic filler include a resin filler having ahomogeneous structure, which is composed of polyethylene, polypropylene,polystyrene, a polyphenylene ether resin, a silicone resin, atetrafluoroethylene resin, or the like; a resin filler of a core-shellstructure having a core layer in a rubber state, which is composed of anacrylic acid ester based resin, a methacrylic acid ester based resin, aconjugated diene based resin, or the like, and a shell layer in avitreous state, which is composed of an acrylic acid ester based resin,a methacrylic acid ester based resin, an aromatic vinyl based resin, avinyl cyanide based resin, or the like; and so on.

Examples of the flame retarder include a halogen-containing flameretarder containing bromine or chlorine; a phosphorus based flameretarder such as triphenyl phosphate, tricresyl phosphate,trisdichloropropyl phosphate, red phosphorus, etc.; a nitrogen basedflame retarder such as guanidine sulfamate, melamine sulfate, melaminepolyphosphate, melamine cyanurate, etc.; a phosphazene based flameretarder such as cyclophosphazene, polyphosphazene, etc.; an inorganicflame retarder such as antimony trioxide, etc.; and so on.

Examples of the ultraviolet ray absorber include a benzotriazole basedultraviolet ray absorber and so on.

Examples of the antioxidant include a hindered phenol based or hinderedamine based antioxidant. Examples of the adhesion enhancer include acoupling agent such as a silane series, a titanate series, an aluminateseries, etc.; and so on.

The thermosetting resin composition of the present invention isimpregnated into or coated on a base material, subsequently subjected toB-staging, and then used as a prepreg. At the time of use for theprepreg, it is preferable to render the thermosetting resin compositionin a state of a varnish in which the respective components are finallydissolved or dispersed in an organic solvent.

Examples of the organic solvent which is used on that occasion includean alcohol based solvent such as methanol, ethanol, propanol, butanol,methyl cellosolve, butyl cellosolve, propylene glycol monomethyl ether,etc.; a ketone based solvent such as acetone, methyl ethyl ketone,methyl isobutyl ketone, cyclohexanone, etc.; an ester based solvent suchas butyl acetate, propylene glycol monomethyl ether acetate, etc.; anether based solvent such as tetrahydrofuran, etc.; an aromatic solventsuch as toluene, xylene, mesitylene, etc.; a nitrogen atom-containingsolvent such as dimethylformamide, dimethylacetamide,N-methylpyrrolidone, etc.; a sulfur atom-containing solvent such asdimethyl sulfoxide, etc.; and so on. These can be used singly or inadmixture of two or more kinds thereof.

Of these, from the standpoint of solubility, methyl ethyl ketone, methylisobutyl ketone, cyclohexanone, methyl cellosolve, and propylene glycolmonomethyl ether are preferable; and from the standpoint of lowtoxicity, methyl isobutyl ketone, cyclohexanone, and propylene glycolmonomethyl ether are more preferable.

Also, at the time of blending in the varnish, it is preferable tosubject the inorganic filler to a pre-treatment with a surface treatingagent such as a coupling agent, e.g., a silane series, a titanateseries, etc., a silicone oligomer, or the like, or to an integral blendtreatment.

A content of the resin composition in the finally obtained varnish ispreferably from 40 to 90% by mass, and more preferably from 50 to 80% bymass of the whole of the varnish. By allowing the content of the resincomposition in the varnish to fall within the range of from 40 to 90% bymass, the coating properties can be kept favorable, and a prepreg havingan appropriate attachment amount of the resin composition can beobtained.

The prepreg of the present invention is one obtained by impregnating orcoating a base material with the thermosetting resin composition of thepresent invention and then performing B-staging. That is, the prepreg ofthe present invention is manufactured by impregnating or coating a basematerial with the thermosetting resin composition of the presentinvention and then performing semi-curing (B-staging) by heating or thelike. The prepreg of the present invention is hereunder described indetail.

For the base material which is used for the prepreg of the presentinvention, well-known materials which are used for various laminateplates for electrical insulating materials can be used. Examples of thematerial include fibers of an inorganic material such as E-glass,D-glass, S-glass, Q-glass, etc.; fibers of an organic material such asaramid, polyester, polytetrafluoroethylene, etc.; mixtures thereof; andso on.

Though such a base material has a form of, for example, a woven fabric,a nonwoven fabric, a roving, a chopped strand mat, a surfacing mat,etc., the material and the shape are selected depending on anapplication or a performance of the target molded article, and thematerial and the shape can be employed solely or in combination of twoor more kinds thereof, as the need arises.

Though the base material is not particularly limited with respect to itsthickness, for example, those having a thickness of from about 0.01 to0.2 mm can be used. Those having been subjected to a surface treatmentwith a silane coupling agent, etc., or those having been subjected to amechanical opening treatment are suitable from the standpoints of heatresistance, moisture resistance, and processability. The prepreg of thepresent invention can be obtained by impregnating or coating the basematerial with the resin composition in such a manner that an attachmentamount thereof relative to the base material is from 20 to 90% by massin terms of a resin content of the prepreg after drying, and thenheating for drying usually at a temperature of from 100 to 200° C. forfrom 1 to 30 minutes to achieve semi-curing (B-staging).

The laminate plate of the present invention is one obtained bylaminating and molding the prepreg of the present invention. That is,the laminate plate is, for example, one obtained by lamination andmolding in a configuration in which from 1 to 20 sheets of the prepregof the present invention are superimposed, and a metal foil such ascopper, aluminum, etc. is disposed on one surface or both surfacesthereof. As for a molding condition, for example, techniques for alaminate plate or multi-layered board for electrical insulatingmaterials can be applied. The molding can be performed within the rangeat a temperature of from 100 to 250° C. under a pressure of from 0.2 to10 MPa for a heating time of from 0.1 to 5 hours by using, for example,a multi-stage press, a multi-stage vacuum press, a continuous moldingmachine, an autoclave molding machine, etc. Also, a multi-layered boardcan be manufactured by combining the prepreg of the present inventionwith a wiring board for internal layer and laminating and molding thecombination.

Next, the laminate plate for wiring boards of the present invention isdescribed.

[Laminate Plate for Wiring Boards]

The laminate plate for wiring boards of the present invention is oneobtained by coating a thermosetting resin composition containing (E) athermosetting resin, (F) silica, and (G) at least one molybdenumcompound selected from zinc molybdate, calcium molybdate, and magnesiummolybdate, with a content of the silica (F) being 20% by volume or moreand not more than 60% by volume, on a base material in a film form orfiber form and then performing semi-curing to form a prepreg, andlaminating and molding the prepreg.

Of these, examples of the thermosetting resin as the component (E)include an epoxy resin, a phenol resin, an unsaturated imide resin, acyanate resin, an isocyanate resin, a benzoxazine resin, an oxetaneresin, an amino resin, an unsaturated polyester resin, an allyl resin, adicyclopentadiene resin, a silicone resin, a triazine resin, a melamineresin, and so on. These can be used singly or in admixture of two ormore kinds thereof.

Of these, from the standpoints of moldability and electrical insulatingproperties, it is preferable to use the epoxy resin alone or inadmixture.

Examples of the epoxy resin which is used include a bisphenol A typeepoxy resin, a bisphenol F type epoxy resin, a bisphenol S type epoxyresin, a phenol novolak type epoxy resin, a cresol novolak type epoxyresin, a bisphenol A novolak type epoxy resin, a bisphenol F novolaktype epoxy resin, a biphenyl type epoxy resin, a xylylene type epoxyresin, a biphenyl aralkyl type epoxy resin, a naphthalene type epoxyresin, a dicyclopentadiene type epoxy resin, an alicyclic epoxy resin, adiglycidyl ether compound of a polyfunctional phenol or a polycyclicaromatic compound such as anthracene, etc., and so on. These can be usedsingly or in admixture of two or more kinds thereof.

In the case of using an epoxy resin as the thermosetting resin, a curingagent or a curing accelerator of the epoxy resin can be used, as theneed arises.

Examples of the curing agent include a polyfunctional phenol compoundsuch as phenol novolak, cresol novolak, etc.; an amine compound such asdicyandiamide, diaminodiphenylmethane, diaminodiphenylsulfone, etc.; anacid anhydride such as phthalic anhydride, pyromellitic anhydride,maleic anhydride, a maleic anhydride copolymer, etc.; and so on. Thesecan be used singly or in admixture of two or more kinds thereof.

Also, examples of the curing accelerator include an imidazole and aderivative thereof, an organic phosphorus based compound, a secondaryamine, a tertiary amine, a quaternary ammonium salt, and so on. Thesecan be used singly or in admixture of two or more kinds thereof.

Examples of the silica as the component (F) include precipitated silicawhich is manufactured by a wet process and which has a high watercontent; and dry process silica which is manufactured by a dry processand which does not substantially contain bonding water, etc. The dryprocess silica includes crushed silica, fumed silica, and fusedspherical silica depending upon a difference of the manufacturingmethod. Of these, from the standpoints of low thermal expansionproperties and high fluidity upon being blended in the resin, fusedspherical silica is preferable.

In the case of using fused spherical silica as the silica, its averageparticle size is preferably from 0.1 μm or more and not more than 1 μm.When the average particle size of the fused spherical silica iscontrolled to 0.1 μm or more, the fluidity at the time of blending inthe resin can be kept favorable, whereas when it is controlled to notmore than 1 μm, the wear of a drill blade at the time of drillingprocessing can be suppressed.

When a cumulative distribution curve by particle size is determinedwhile defining the whole volume of the particles as 100%, the “averageparticle size” as referred to in this specification means a particlesize corresponding to just 50% of the volume, and it can be measured bya particle size distribution analyzer adopting a laser diffractionscattering method, or the like.

It is necessary that a content of the silica is 20% by volume or moreand not more than 60% by volume of the whole of the resin composition.When the content of the silica is controlled to 20% by volume or more ofthe whole of the resin composition, low thermal expansion of thelaminate plate can be realized, whereas when it is controlled to notmore than 60% by volume, the moldability and drilling processability canbe kept favorable. The content of the silica is preferably 30% by volumeor more and not more than 60% by volume, and more preferably 40% byvolume or more and not more than 56% by volume.

It is necessary to use, as the component (G), at least one molybdenumcompound selected from zinc molybdate, calcium molybdate, and magnesiummolybdate.

At the time of using such a molybdenum compound together with the silicafor a laminate plate, the effect for preventing a lowering of thedrilling processability is larger than that in burnt talc or the like,and the electrical insulating properties are not significantly loweredunlikely those in molybdenum disulfide. At the time of blending such amolybdenum compound, a particle thereof may be used as it is, or such amolybdenum compound may be used upon being supported on a particle oftalc, silica, zinc oxide, calcium carbonate, magnesium hydroxide, or thelike. On that occasion, an average particle size of such a particle ispreferably 0.3 μm or more and not more than 3 μM, and more preferably0.5 μm or more and not more than 2 μm.

When the average particle size is controlled to 0.3 μm or more, thedispersibility at the time of blending in the resin can be keptfavorable, whereas when it is controlled to not more than 3 μm, theabrupt precipitation in the case of dissolving the resin composition inan organic solvent to form a varnish can be prevented from occurring.

A content of the molybdenum compound is preferably 0.1% by volume ormore and not more than 10% by volume, and more preferably 0.2% by volumeor more and not more than 7% by volume of the whole of the resincomposition.

When the content of the molybdenum compound is controlled to 0.1% byvolume or more, the drilling processability of a laminate plate can bekept favorable, whereas when it is controlled to not more than 10% byvolume, a lowering of the moldability can be prevented from occurring.

In the thermosetting resin composition according to the presentinvention, in addition to the foregoing, known thermoplastic resin,elastomer, inorganic filler, organic filler, flame retarder, ultravioletray absorber, antioxidant, and adhesion enhancer, and the like can bearbitrarily used.

Examples of such a thermoplastic resin include polyethylene,polypropylene, polystyrene, a polyphenylene ether resin, a phenoxyresin, a polycarbonate resin, a polyester resin, a polyamide resin, apolyamide-imide resin, a polyimide resin, a xylene resin, apolyphenylene sulfide resin, a polyether imide resin, apolyetheretherketone resin, a polyether imide resin, a silicone resin, atetrafluoroethylene resin, and so on.

Examples of the elastomer include polybutadiene, acrylonitrile,epoxy-modified polybutadiene, maleic anhydride-modified polybutadiene,phenol-modified polybutadiene, carboxy-modified acrylonitrile, and soon.

Examples of the inorganic filler include alumina, talc, mica, kaolin,aluminum hydroxide, magnesium hydroxide, zinc borate, zinc stannate,zinc oxide, titanium oxide, boron nitride, calcium carbonate, bariumsulfate, aluminum borate, potassium titanate, a glass powder of E-glass,S-glass, D-glass, etc., a hollow glass bead, and so on.

Examples of the organic filler include a resin particle having ahomogeneous structure, which is composed of polyethylene, polypropylene,polystyrene, a polyphenylene ether resin, a silicone resin, atetrafluoroethylene resin, or the like; a resin particle of a core-shellstructure having a core layer in a rubber state, which is composed of anacrylic acid ester based resin, a methacrylic acid ester based resin, aconjugated diene based resin, or the like, and a shell layer in avitreous state, which is composed of an acrylic acid ester based resin,a methacrylic acid ester based resin, an aromatic vinyl based resin, avinyl cyanide based resin, or the like; and so on.

Examples of the flame retarder include a halogen-containing flameretarder containing bromine or chlorine; a phosphorus based flameretarder such as triphenyl phosphate, tricresyl phosphate,trisdichloropropyl phosphate, red phosphorus, etc.; a nitrogen basedflame retarder such as guanidine sulfamate, melamine sulfate, melaminepolyphosphate, melamine cyanurate, etc.; a phosphazene based flameretarder such as cyclophosphazene, polyphosphazene, etc.; an inorganicflame retarder such as antimony trioxide, etc.; and so on.

Examples of the ultraviolet ray absorber include a benzotriazole basedultraviolet ray absorber and so on; examples of the antioxidant includea hindered phenol based or hindered amine based antioxidant; andexamples of the adhesion enhancer include a coupling agent such as asilane series, a titanate series, and an aluminate series, and so on.

The laminate plate for wiring boards of the present invention can beobtained by laminating and molding a material obtained by coating thethermoplastic resin composition using the foregoing components accordingto the present invention on a base material in a film form or fiberform, followed by semi-curing. At the time of coating the thermosettingresin composition according to the present invention, it is preferableto use the subject thermosetting resin composition after being dissolvedin an organic solvent to form a varnish. By coating the resincomposition after being varnished, a laminate plate which is homogenousand less in a defect such as a void, etc. can be obtained.

Examples of the organic solvent which is used at the time of varnishingthe thermosetting resin composition include an alcohol based solventsuch as methanol, ethanol, propanol, butanol, methyl cellosolve, butylcellosolve, propylene glycol monomethyl ether, etc.; a ketone basedsolvent such as acetone, methyl ethyl ketone, methyl isobutyl ketone,cyclohexanone, etc.; an ester based solvent such as butyl acetate,propylene glycol monomethyl ether acetate, etc.; an ether based solventsuch as tetrahydrofuran, etc.; an aromatic solvent such as toluene,xylene, mesitylene, etc.; a nitrogen atom-containing solvent such asdimethylformamide, dimethylacetamide, N-methylpyrrolidone, etc.; asulfur atom-containing solvent such as dimethyl sulfoxide, etc.; and soon. These can be used singly or in admixture of two or more kindsthereof.

Of these, from the standpoint of solubility of the resin, methylcellosolve, propylene glycol monomethyl ether, methyl ethyl ketone,methyl isobutyl ketone, and cyclohexanone are preferable; and from thestandpoint of low toxicity, propylene glycol monomethyl ether, methylisobutyl ketone, and cyclohexanone are more preferable.

A proportion of the resin composition in the varnish is preferably 50%by mass or more and not more than 80% by mass of the whole of thevarnish. By allowing the proportion of the resin composition in thevarnish to fall within the range of 50% by mass or more and not morethan 80% by mass, the coating properties on the base material can bekept favorable.

As for the base material which is used at the time of coating, examplesof the base material in a film form include a metal foil made of copper,aluminum, etc.; and an organic film made of polyethylene terephthalate,polyimide, etc. Examples of the base material in a fiber form includefibers of an inorganic material such as E-glass, D-glass, S-glass,Q-glass, etc.; fibers of an organic material such as aramid, polyester,polytetrafluoroethylene, etc.; and mixtures thereof such as a wovenfabric, a nonwoven fabric, a roving mat, a chopped strand mat, and asurfacing mat.

Above all, it is preferable to use a woven fabric of fibers of aninorganic material such as E-glass, S-glass, D-glass, Q-glass, etc.,namely a glass cloth. By using a glass cloth as the base material, it ispossible to satisfy both low thermal expansion and high drillingprocessability of the laminate plate.

In the case of using a glass cloth as the base material, those havingbeen subjected to a mechanical opening treatment, or those having beensubjected to a surface treatment with a coupling agent, etc. can be usedin a thickness of from 0.01 mm to 0.2 mm.

In order to obtain a prepreg by coating a thermoplastic resincomposition varnish on a glass cloth and semi-curing it, for example,there can be adopted a method in which after the glass cloth is dippedin the resin composition varnish to impregnate the varnish therein, anattachment amount of the varnish is adjusted using a cut bar, a squeezeroll, or the like such that a proportion of the resin composition in theprepreg is from 20% by mass to 90% by mass, and the resultant issubsequently allowed to pass through a drying furnace at from about 100°C. to 200° C. for from about one minute to 30 minutes, thereby achievingsemi-curing, or the like.

In order to obtain the laminate plate of the present invention bylaminating and molding the thus obtained prepreg, for example, there canbe adopted a method in which from 1 to 20 sheets of the prepreg aresuperimposed so as to have a required thickness, a metal foil such ascopper, aluminum, etc. is disposed on one surface or both surfacesthereof, and heat pressure molding is performed under a condition at atemperature of from about 100 to 250° C. under a pressure of from about0.2 to 10 MPa for from about 0.1 to 5 hours by using a multi-stagepress, a multi-stage vacuum press, a continuous molding machine, anautoclave molding machine, etc., or the like.

Next, a manufacturing method of the resin composition varnish of thepresent invention is described.

[Manufacturing Method of Resin Composition Varnish]

The manufacturing method of the resin composition varnish of the presentinvention includes a first dispersing and mixing step of dispersing andmixing (I) a molybdenum compound in (H) a slurry containing a prescribedsilica particle, a second dispersing and mixing step of dispersing andmixing the slurry having gone through the first dispersing and mixingstep in a varnish containing (J) a thermosetting resin, and a thirddispersing and mixing step of dispersing and mixing (K) an inorganicfiller in the varnish having gone through the second dispersing andmixing step.

(First Dispersing and Mixing Step)

The silica particle in the slurry (H) in the first dispersing and mixingstep is required to have an average particle size of 0.01 μm or more andnot more than 0.1 μm and a specific surface area of 30 m²/g or more andnot more than 270 m²/g.

When the average particle size is 0.01 μm or more and not more than 0.1μm, and the specific surface area is 30 m²/g or more and not more than270 m²/g, at the time of dispersing and mixing the molybdenum compound,the molybdenum compound can be stably kept in a finely dispersed statesuch that it does not precipitate over a long period of time.

Incidentally, when a cumulative distribution curve by particle size isdetermined while defining the whole volume of the particles as 100%, the“average particle size” as referred to in this specification means aparticle size corresponding to just 50% of the volume, and it can bemeasured by a particle size distribution analyzer adopting a laserdiffraction scattering method, or the like.

Also, the “specific surface area” refers to a total sum of surface areasof the whole of particles contained in the powder per unit mass, and itcan be measured by a specific surface area analyzer adopting the BETmethod, or the like.

Examples of the organic solvent in the slurry include an alcohol such asmethanol, ethanol, propanol, butanol, etc.; a glycol ether such asmethyl cellosolve, butyl cellosolve, propylene glycol monomethyl ether,etc.; and a ketone such as acetone, methyl ethyl ketone, methyl isobutylketone, cyclohexanone, etc.

Of these, from the standpoint that the dispersibility of the molybdenumcompound is easily kept in the second dispersing and mixing step, anorganic solvent the same as the organic solvent which is used for thevarnish containing (J) a thermosetting resin is preferable.

A blending amount of the silica particle in the slurry is preferably 10%by mass or more and not more than 50% by mass, and more preferably 20%by mass or more and not more than 40% by mass. When the blending amountis 10% by mass or more and not more than 50% by mass, the dispersibilityof the silica particle in the slurry is excellent, and thedispersibility and stability of the molybdenum compound are favorable.

As the silica slurry satisfying the foregoing requirements, for example,there can be exemplified ADMANANO, manufactured by Admatechs CompanyLimited.

Examples of the molybdenum compound (I) include molybdenum trioxide,zinc molybdate, ammonium molybdate, magnesium molybdate, calciummolybdate, barium molybdate, sodium molybdate, potassium molybdate,phosphomolybdic acid, ammonium phosphomolybdate, sodiumphosphomolybdate, silicomolybdic acid, molybdenum disulfide, molybdenumdiselenide, molybdenum ditelluride, molybdenum boride, molybdenumdisilicide, molybdenum nitride, molybdenum carbide, and so on. These canbe used singly or in admixture of two or more kinds thereof.

Of these, zinc molybdate, calcium molybdate, and magnesium molybdate arepreferable because these compounds have low water solubility and lowtoxicity, have high electrical insulating properties, and have a largeimproving effect of drilling processability.

In the case of defining the volume of the silica particle contained inthe slurry as 1, a blending amount of the molybdenum compound in thesilica slurry is preferably 0.2 or more and not more than 5, and morepreferably 0.3 or more and not more than 4 in terms of a volume ratio(Mo compound/SiO₂). When the volume ratio is 0.2 or more and not morethan 5, at the time of dispersing and mixing the molybdenum compound inthe slurry, the dispersibility and stability are favorable.

Examples of a method for dispersing and mixing the molybdenum compoundin the silica slurry in the first dispersing and mixing step include amethod in which the molybdenum compound is first gradually added andwell mixed while stirring the slurry, and the mixture is subsequentlysubjected to a dispersion treatment by a media mill such as a bead mill,a ball mill, etc., a high-speed disperser such as a dissolver, etc., ahigh-pressure homogenizer such as a nanomizer, etc., a colloid mill, anultrasonic processor, or the like.

Above all, a method for performing the treatment by a high-speedhomogenizer is preferable because incorporation of impurities is small,and the dispersion can be efficiently achieved. Also, a coupling agentsuch as a silane series, a titanate series, an aluminate series, etc., amodified silicone such as polyether-modified polysiloxane, etc., apolycarboxylic acid, a polymer dispersant such as a urethane series, anacrylate series, etc., or the like can also be added as a dispersant atthe time of dispersing and mixing.

(Second Dispersing and Mixing Step)

Examples of the thermosetting resin (J) in the step of the seconddispersing and mixing step include an epoxy resin, a phenol resin, anunsaturated imide resin, a cyanate resin, an isocyanate resin, abenzoxazine resin, an oxetane resin, an amino resin, an unsaturatedpolyester resin, an allyl resin, a dicyclopentadiene resin, a siliconeresin, a triazine resin, a melamine resin, and so on. These can be usedsingly or in admixture of two or more kinds thereof.

Of these, an epoxy resin is preferable from the standpoints ofmoldability and electrical insulating properties.

Examples of such an epoxy resin include a bisphenol A type epoxy resin,a bisphenol F type epoxy resin, a bisphenol S type epoxy resin, a phenolnovolak type epoxy resin, a cresol novolak type epoxy resin, a bisphenolA novolak type epoxy resin, a bisphenol F novolak type epoxy resin, abiphenyl type epoxy resin, a xylylene type epoxy resin, a biphenylaralkyl type epoxy resin, a naphthalene type epoxy resin, adicyclopentadiene type epoxy resin, an alicyclic epoxy resin, adiglycidyl ether compound of a polyfunctional phenol or a polycyclicaromatic compound such as anthracene, etc., and so on. These can be usedsingly or in admixture of two or more kinds thereof.

In the case of using an epoxy resin as the thermosetting resin, a curingagent of the epoxy resin can be used, as the need arises.

Examples of the curing agent include a polyfunctional phenol compoundsuch as phenol novolak, cresol novolak, etc.; an amine compound such asdicyandiamide, diaminodiphenylmethane, diaminodiphenylsulfone, etc.; anacid anhydride such as phthalic anhydride, pyromellitic anhydride,maleic anhydride, a maleic anhydride copolymer, etc.; and so on. Thesecan be used singly or in admixture of two or more kinds thereof.

Examples of the organic solvent which is used for the varnish containinga thermosetting resin include an alcohol based solvent such as methanol,ethanol, propanol, butanol, methyl cellosolve, butyl cellosolve,propylene glycol monomethyl ether, etc.; a ketone based solvent such asacetone, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone,etc.; an ester based solvent such as butyl acetate, propylene glycolmonomethyl ether acetate, etc.; an ether based solvent such astetrahydrofuran, etc.; an aromatic solvent such as toluene, xylene,mesitylene, etc.; a nitrogen atom-containing solvent such asdimethylformamide, dimethylacetamide, N-methylpyrrolidone, etc.; asulfur atom-containing solvent such as dimethyl sulfoxide, etc.; and soon. These can be used singly or in admixture of two or more kindsthereof.

Of these, from the standpoints of excellent solubility of thethermosetting resin and low toxicity, methyl ethyl ketone, methylisobutyl ketone, cyclohexanone, and propylene glycol monomethyl etherare preferable.

A solid content concentration of the varnish containing a thermosettingresin is preferably 40% by mass or more and not more than 90% by mass,and more preferably 50% by mass or more and not more than 80% by mass.By allowing the solid content of the varnish to fall within the range of40% by mass or more and not more than 90% by mass, the dispersibilityand stability of the molybdenum compound in the second dispersing andmixing step can be kept favorable.

When the whole of the resin composition excluding the organic solventfinally contained in the resin composition varnish is defined as 100% byvolume, a blending amount of the slurry having the molybdenum compounddispersed therein into the varnish is preferably 0.1% by volume or moreand not more than 10% by volume in terms of an amount of the molybdenumcompound. By allowing the amount of the molybdenum compound to fallwithin the range of 0.1% by volume or more and not more than 10% byvolume, it is possible to realize low thermal expansion of the resincomposition while keeping the drilling processability favorable.

Examples of a method for dispersing and mixing the slurry having themolybdenum compound dispersed therein in the varnish containing athermosetting resin in the second dispersing and mixing step include amethod in which the slurry is gradually added and well mixed whilestirring the varnish.

(Third Dispersing and Mixing Step)

As the inorganic filler (K) in the third dispersing and mixing step,various material exclusive of the silica particle as thealready-described component (H) and the molybdenum compound as thealready-described component (I) can be used. Examples thereof includesilica, alumina, talc, mica, kaolin, aluminum hydroxide, magnesiumhydroxide, zinc borate, zinc stannate, zinc oxide, titanium oxide, boronnitride, calcium carbonate, barium sulfate, aluminum borate, potassiumtitanate, a glass powder of E-glass, S-glass, D-glass, etc., a hollowglass bead, and so on. These can be used singly or in admixture of twoor more kinds thereof.

Of these, silica is preferable from the standpoint of its lowcoefficient of thermal expansion.

Examples of the silica include precipitated silica which is manufacturedby a wet process and which has a high water content; and dry processsilica which is manufactured by a dry process and which does notsubstantially contain bonding water, etc. Furthermore, the dry processsilica includes crushed silica, fumed silica, and fused spherical silicadepending upon a difference of the manufacturing method. Of these, fromthe standpoint of excellent fluidity upon being filled in the resin,fused spherical silica is preferable.

In the case of using fused spherical silica as the inorganic filler, itsaverage particle size is preferably from 0.1 μm or more and not morethan 10 μm, and more preferably from 0.3 μm or more and not more than 8μm. When the average particle size of the fused spherical silica iscontrolled to 0.1 μm or more, the fluidity at the time of filling in theresin can be kept favorable, whereas when it is controlled to not morethan 10 μm, a probability of incorporation of coarse particles isreduced, thereby enabling one to suppress the generation of failure.

Incidentally, the average particle size is made to be larger than thatof the silica particle as the already-described component (H).

When the whole of the resin composition excluding the organic solventfinally contained in the resin composition varnish is defined as 100% byvolume, a blending amount of the inorganic filler into the varnish ispreferably 20% by volume or more and not more than 60% by volume, andmore preferably 30% by volume or more and not more than 55% by volume.By allowing the blending amount of the inorganic filler to fall withinthe range of 20% by volume or more and not more than 60% by volume, itis possible to realize low thermal expansion of the resin compositionwhile keeping the moldability favorable.

Examples of a method for dispersing and mixing the inorganic filler inthe varnish containing the molybdenum compound and the thermosettingresin in the third dispersing and mixing step include a method in whichthe inorganic filler is added as it is and mixed; and a method in whichthe inorganic filler is dispersed in the organic solvent in advance toform a slurry, which is then added and mixed.

Of these, from the standpoint of dispersibility of the inorganic fillerin the varnish, a method in which the inorganic filler is converted intoa slurry and then added is preferable. At the time of converting theinorganic filler into a slurry, it is preferable to subject theinorganic filler to a pre-treatment with a surface treating agent suchas a coupling agent, e.g., a silane series, a titanate series, etc., asilicone oligomer, or the like in advance, or to an integral blendtreatment.

In the resin composition varnish having been manufactured through theforegoing respective steps, in addition to the foregoing components, acuring accelerator, a thermoplastic resin, an elastomer, an organicfiller, aflame retarder, an ultraviolet ray absorber, an antioxidant, anadhesion enhancer, and the like can be added and used.

Examples of the curing accelerator include an imidazole and a derivativethereof, an organic phosphorus based compound, a secondary amine, atertiary amine, a quaternary ammonium salt, and so on. These can be usedsingly or in admixture of two or more kinds thereof.

Examples of the thermoplastic resin include polyethylene, polypropylene,polystyrene, a polyphenylene ether resin, a phenoxy resin, apolycarbonate resin, a polyester resin, a polyamide resin, apolyamide-imide resin, a polyimide resin, a xylene resin, apolyphenylene sulfide resin, a polyether imide resin, apolyetheretherketone resin, a polyether imide resin, a silicone resin, atetrafluoroethylene resin, and so on.

Examples of the elastomer include polybutadiene, acrylonitrile,epoxy-modified polybutadiene, maleic anhydride-modified polybutadiene,phenol-modified polybutadiene, carboxy-modified acrylonitrile, and soon.

Examples of the organic filler include a resin filler having ahomogeneous structure, which is composed of polyethylene, polypropylene,polystyrene, a polyphenylene ether resin, a silicone resin, atetrafluoroethylene resin, or the like; a resin filler of a core-shellstructure having a core layer in a rubber state, which is composed of anacrylic acid ester based resin, a methacrylic acid ester based resin, aconjugated diene based resin, or the like, and a shell layer in avitreous state, which is composed of an acrylic acid ester based resin,a methacrylic acid ester based resin, an aromatic vinyl based resin, avinyl cyanide based resin, or the like; and so on.

Examples of the flame retarder include a halogen-containing flameretarder containing bromine or chlorine; a phosphorus based flameretarder such as triphenyl phosphate, tricresyl phosphate,trisdichloropropyl phosphate, red phosphorus, etc.; a nitrogen basedflame retarder such as guanidine sulfamate, melamine sulfate, melaminepolyphosphate, melamine cyanurate, etc.; a phosphazene based flameretarder such as cyclophosphazene, polyphosphazene, etc.; an inorganicflame retarder such as antimony trioxide, etc.; and so on.

Besides, examples of the ultraviolet ray absorber include abenzotriazole based ultraviolet ray absorber and so on; examples of theantioxidant include a hindered phenol based or hindered amine basedantioxidant; and examples of the adhesion enhancer include a couplingagent such as a silane series, a titanate series, an aluminate series,etc.

Incidentally, it is preferable to carry out the addition of thesecomponents to the resin composition varnish after the third dispersingand mixing step. Also, a solid content of the finally obtained resincomposition varnish is preferably from 40 to 80% by mass, and morepreferably from 45 to 75% by mass.

When the solid content is from 40 to 80% by mass, the coating propertiesof the varnish are favorable, and a prepreg having an appropriateattachment amount of the resin composition can be obtained.

[Prepreg and Laminate Plate]

Next, a prepreg and a laminate plate each using the foregoing resincomposition varnish are described.

(Prepreg)

The prepreg of the present invention is one obtained by impregnating orcoating a base material with the resin composition varnish obtained bythe already-described method for manufacturing a resin compositionvarnish of the present invention and then performing semi-curing(B-staging) by heating or the like.

Examples of the base material which is used for the prepreg of thepresent invention include fibers of an inorganic material such asE-glass, D-glass, S-glass, Q-glass, etc.; fibers of an organic materialsuch as an aramid resin, a polyester resin, a tetrafluoroethylene resin,etc.; and mixtures thereof.

Though such a base material has a form of, for example, a woven fabric,a nonwoven fabric, a roving, a chopped strand mat, a surfacing mat,etc., the material and the shape are selected depending on anapplication or a performance of the target laminate plate, and thematerial and the shape can be employed solely or in combination of twoor more kinds thereof, as the need arises. Also, those having beensubjected to a surface treatment with a silane coupling agent, etc., orthose having been subjected to a mechanical opening treatment arepreferable from the standpoints of heat resistance, moisture resistance,and processability. As for a thickness of the base material, forexample, those having a thickness of from 0.01 to 0.2 mm can be used.

(Laminate Plate)

The laminate plate of the present invention is one obtained bylamination and molding by using the prepreg of the present invention.For example, a metal clad laminate plate can be manufactured byperforming lamination and molding in a configuration in which from 1 to20 sheets of the prepreg of the present invention are superimposed, anda metal foil such as copper, aluminum, etc. is disposed on one surfaceor both surfaces thereof, within the range at a temperature of fromabout 100 to 250° C. under a pressure of from about 0.2 to 10 MPa for aheating time of from about 0.1 to 5 hours by using a press, a vacuumpress, a continuous molding machine, an autoclave molding machine, orthe like.

The metal foil is not particularly limited so far as it is one to beused for an application of electronic components. Also, a multi-layeredboard can be manufactured by combining the prepreg of the presentinvention with a wiring board for internal layer and laminating andmolding the combination.

Each of the above-described prepreg and laminate plate of the presentinvention has such characteristic features as a low coefficient ofthermal expansion and high drilling processability.

EXAMPLES

Next, the present invention is described in more detail with referenceto the following Examples, but it should be construed that theseExamples do not limit the present invention.

Manufacturing Example 1 Manufacture of Maleimide Compound (A-1)

In a reaction vessel having a capacity of 2 liters and capable of beingheated and cooled, which was equipped with a thermometer, an agitator,and a reflux condenser-equipped water quantity meter, 358.0 g ofbis(4-maleimidophenyl)methane, 54.5 g of p-aminophenol, and 412.5 g ofpropylene glycol monomethyl ether were charged and allowed to react witheach other for 5 hours while refluxing, thereby obtaining a maleimidecompound (A-1).

Manufacturing Example 2 Manufacture of Maleimide Compound (A-2)

In a reaction vessel having a capacity of 2 liters and capable of beingheated and cooled, which was equipped with a thermometer, an agitator,and a reflux condenser-equipped water quantity meter, 358.0 g ofbis(4-maleimidophenyl)methane, 68.5 g of p-aminobenzoic acid, and 322.5g of N-dimethylacetamide were charged and allowed to react with eachother at 140° C. for 5 hours, thereby obtaining a maleimide compound(A-2).

Examples 1 to 3

The unsaturated maleimide compound (A) having an acidic substituentobtained in Manufacturing Example 1 or 2, and (B) a thermosetting resinand a curing accelerator, (C) an inorganic filler, and (D) a molybdenumcompound as described below were dispersed and dissolved in a blendingproportion shown in Table 1 in propylene glycol monomethyl ether,thereby obtaining a homogeneous varnish having a content of the resincomposition of 70% by mass. This resin composition varnish wasimpregnated and coated on an E-glass cloth [WEA116E, manufactured byNitto Boseki Co., Ltd.] having a thickness of 0.1 mm, followed byheating for drying at 150° C. for 5 minutes to obtain a prepreg having acontent of the resin composition of 50% by mass. Four sheets of thisprepreg were superimposed, and an 18 μm-thick electrolytic copper foilwas disposed on the top and bottom, followed by vacuum pressing under apressure of 3.5 MPa at a temperature of 185° C. for 90 minutes, therebyobtaining a copper clad laminate plate.

Each of the obtained copper clad laminate plates was used and thenmeasured and evaluated with respect to drilling processability,coefficient of thermal expansion, and heat resistance by the followingmethods. The results are shown in Table 1.

(B) Thermosetting Resin:

B-1: Biphenyl aralkyl type epoxy resin [NC-3000, manufactured by NipponKayaku Co., Ltd.]

B-2: Phenol novolak type epoxy resin [EPICLON N-770, manufactured by DICCorporation]

B-3: Cresol novolak type phenol resin [PHENOLITE KA-1165, manufacturedby DIC Corporation]

Curing accelerator: 2-Ethyl-4-methyl imidazole [2E4MI, manufactured byShikoku Chemicals Corporation]

(C) Inorganic Filler:

C-1: Fused spherical silica slurry [SC2050-KC, manufactured by AdmatechsCompany Limited, average particle size: 0.5 μm, solid content: 70% bymass]

C-2: Aluminum hydroxide [CL-310, manufactured by Sumitomo Chemical Co.,Ltd.]

C-3: Burnt talc [ST-100, manufactured by Fuji Talc Industrial Co., Ltd.]

(D) Molybdenum Compound:

D-1: Zinc molybdate [a reagent, manufactured by Strem Chemicals Inc.]

D-2: Zinc molybdate-supported talc [KEMIGARD 911C, manufactured bySherwin-Williams Company, zinc molybdate: 20% by mass]

D-3: Calcium molybdate [a reagent, manufactured by Strem Chemicals Inc.]

Comparative Example 1

A copper clad laminate plate using a resin composition was obtained inthe same manner as that in Example 1, except that the molybdenumcompound (D) was not blended. The measurement and evaluation results areshown in Table 1.

Comparative Example 2

A copper clad laminate plate using a resin composition was obtained inthe same manner as that in Example 1, except that the unsaturatedmaleimide compound (A) having an acidic substituent was not blended. Themeasurement and evaluation results are shown in Table 1.

Comparative Example 3

A copper clad laminate plate using a resin composition was obtained inthe same manner as that in Example 1, except that the inorganic filler(C) was not blended. The measurement and evaluation results are shown inTable 1.

<Evaluation of Drilling Processability, Coefficient of ThermalExpansion, and Heat Resistance of Copper Clad Laminate Plate> (1)Evaluation of Drilling Processability:

Two sheets of the copper clad laminate plate were superimposed; analuminum foil having a thickness of 0.1 mm was disposed thereabove,whereas a paper phenol board having a thickness of 1.5 mm was disposedthereunder; 6,000 holes were drilled with a drill having a diameter of0.2 mm by using a drilling machine [ND-1V212, manufactured by HitachiVia Mechanics, Ltd.] under a condition at a rotation number of 160 krpmand a feed rate of 2 m/min under a chip load of 12.5 μm/rev; and a wearamount of drill cutting blade and hole registration accuracy weremeasured by the following methods, thereby evaluating the drillingprocessability.

(a) Wear Amount of Drill Cutting Blade:

A drilling cutting blade portion before and after drilling was observedfrom the drill central axis by using an inspection microscope [MX50,manufactured by Olympus Corporation], and a wear retreat amount ofcutting blade edge was measured and defined as the wear amount of drillcutting blade.

(b) Hole Registration Accuracy:

Of the two-ply copper clad laminate plates, a registration deviationamount of holes of the lower side (drill exit side) of the second sheetwas measured using a hole registration accuracy analyzer [HT-1AM,manufactured by Hitachi Via Mechanics, Ltd.], and average +3σ (σ:standard deviation) of registration deviation amounts of the 4,001st to6,000th hit holes was calculated and defined as the hole registrationaccuracy.

(2) Measurement of Coefficient of Thermal Expansion:

After removing the copper foil of the copper clad laminate plate with anetching liquid, the resulting laminate plate was cut into a size of 5 mmsquare, thereby fabricating a specimen. A coefficient of thermalexpansion of this specimen in the machine direction (longitudinaldirection of the glass cloth) at from 50° C. to 120° C. was measured ata temperature rising rate of 10° C./min by using a TMA test apparatus(TMA2940, manufactured by TA Instruments).

(3) Evaluation of Heat Resistance (Glass Transition Temperature):

After removing the copper foil of the copper clad laminate plate with anetching liquid, the resulting laminate plate was cut into a size of 5 mmsquare, thereby fabricating a specimen. A temperature-dimension changecurve of this specimen in the thickness direction was measured at atemperature rising rate of 10° C./min by using a TMA test apparatus(TMA2940, manufactured by Du Pont) and a temperature of a point ofintersection between an approximate straight line of low temperatureside and an approximate straight line of high temperature side in thetemperature-dimension change curve was determined as a glass transitiontemperature and evaluated for the heat resistance.

TABLE 1 Example Example Example Comparative Comparative Comparative 1 23 Example 1 Example 2 Example 3 Use amount (parts by mass) A.Unsaturated maleimide compound having an acidic substituent A-1(Manufacturing Example 1) 65 65 65 65 A-2 (Manufacturing Example 2) 50B: Thermosetting resin B-1 (Biphenyl aralkyl type epoxy resin) 35 35 3535 B-2 (Phenol novolak type epoxy resin) 50 61 B-3 (Cresol novolak typephenol resin) 39 Curing accelerator: 2-Ethyl-4-methyl 0.5 0.25 0.5 0.50.15 0.5 imidazole C: Inorganic filler C-1 (Fused spherical silicaslurry: 199 124 81 199 124 SC2050-KC) C-2: (Aluminum hydroxide: CL-310)34 34 C-3: (Burnt talc: ST-100) 48 54 D: Molybdenum compound D-1 (Zincmolybdate) 86 154 D-2 (Zinc molybdate-supported talc, 6.0 6.0 10%supported) D-3 (Calcium molybdate) 5.6 Composition (% by volume) A + B:Unsaturated maleimide compound + 50 60 79 50 60 70 Thermosetting resinC: Inorganic filler 38 38.5 20 38 38.5 D: Molybdenum compound 12 1.5 1.012 1.5 30 Measurement and evaluation 1) Drilling processability Wearamount of drill cutting blade (μm) 11 9 7 31 8 5 Hole registrationaccuracy (μm) 31 30 28 48 29 25 2) Coefficient of thermal expansion(10⁻⁶/° C.) 10.8 11.4 11.7 10.7 14.1 14.5 3) Heat resistance (glasstransition 210 220 215 212 175 199 temperature: ° C.)

The use amount (parts by mass) in Table 1 is a blending amount of eachof the components regarding the resin compositions of the Examples andComparative Examples, as expressed in terms of parts by mass in the casewhere a total sum blending amount of the unsaturated maleimide compound(A) having an acidic substituent and the thermosetting resin (B) isdefined as 100 parts by mass. However, in Comparative Example 2, sincethe maleimide compound (A) is not blended, the total sum blending amountof the thermosetting resin (B) and the cresol novolak type phenol resinwas shown as 100 parts by mass.

As is clear from Table 1, all of the Examples of the present inventionare low in the coefficient of thermal expansion and excellent in thedrilling processability and heat resistance.

On the other hand, though Comparative Example 1 is low in thecoefficient of thermal expansion and excellent in the heat resistance,it is significantly inferior in the drilling processability because themolybdenum compound (D) of the present invention is not containedtherein.

Also, though Comparative Examples 2 and 3 are excellent in the drillingprocessability, they are high in the coefficient of thermal expansionand inferior in the heat resistance because the unsaturated maleimidecompound (A) having an acidic substituent or the inorganic filler (C) ofthe present invention is not contained therein.

Examples 4, 6 and 7 and Comparative Example 4

In blends shown in Tables 2 and 3, first of all, (E) a thermosettingresin and a curing agent were completely dissolved in an organicsolvent; subsequently, (F) a silica slurry was added; and stirring wasperformed until the both were thoroughly mixed. Thereafter, (G) amolybdenum compound was gradually added; stirring was continued until anaggregated block disappeared; and finally, a curing accelerator wasadded, and stirring was performed for one hour such that the whole ofthe varnish became homogenous.

Each of the thus obtained thermosetting resin composition varnishes wasimpregnated and coated on an E-glass cloth (WEA116E, manufactured byNitto Boseki Co., Ltd.) having a thickness of 0.1 mm, followed byheating for drying at 160° C. for 5 minutes to achieve semi-curing,thereby obtaining a prepreg having a proportion of the resin compositionof 48% by mass.

A prescribed number of sheets of this prepreg were superimposed so as tobe a required thickness, an electrolytic copper foil [GTS-12,manufactured by Furukawa Electric Co., Ltd.] having a thickness of 12 μmwas disposed on the both surfaces, followed by heat pressure moldingunder a pressure of 4 MPa at a temperature of 185° C. for 90 minutes byusing a vacuum press, thereby obtaining a copper clad laminate plate.

Example 5 and Comparative Example 5

Copper clad laminate plates were obtained in the same manner as that inExamples 4, 6 and 7 and Comparative Example 4, except that at the timeof blending the thermosetting resin composition varnish, after addingthe silica slurry (F) and before adding the molybdenum compound (G), aninorganic filler (aluminum hydroxide) was added, and the components werethoroughly stirred and mixed.

Comparative Examples 6 and 7

Copper clad laminate plates were obtained in the same manner as that inExamples 4, 6 and 7 and Comparative Example 4, except that at the timeof blending the thermosetting resin composition varnish, after addingthe silica slurry (F), an inorganic filler (burnt talc or molybdenumdisulfide) was added; the components were stirred until an aggregatedblock disappeared; and finally, a curing accelerator was added, andstirring was performed for one hour such that the whole of the varnishbecame homogenous.

TABLE 2 Component Example 4 Example 5 Example 6 Example 7 (E)Thermosetting E-1 100 100 resin E-2 60 60 E-3 40 40 Curing agent 52 6352 63 Curing accelerator 0.3 0.2 0.32 0.25 (F) Silica F-1 170 (23) 391(49) 282 (40) F-2 558 (56) (G) Molybdenum G-1 54.6 (4)   compound G-213.1 (2)   G-3 10.4 (1)   G-4  4.5 (0.5) Inorganic filler 3 96 Organicsolvent 89 117 70 72

TABLE 3 Com- Com- Com- Com- parative parative parative parativeComponent Example 4 Example 5 Example 6 Example 7 (E) Thermosetting E-1100 100 resin E-2 60 60 E-3 40 40 Curing agent 52 63 52 63 Curingaccelerator 0.25 0.2 0.32 0.35 (F) Silica F-1 110 (15) 391 (49) 282 (40)F-2 824 (62) (G) Molybdenum G-1 146 (8)  compound G-2 6.6 (1)  Inorganicfiller 1 8.1 Inorganic filler 2 5.4 Inorganic filler 3 148 Organicsolvent 128 136 69 72

Here, a blending amount of each of the components in Tables 2 and 3 wasexpressed in terms of parts by mass in the case where a total sumblending amount of the thermosetting resin (E) as defined as 100.However, with respect to the silica (F) and the molybdenum compound (G),a value of % by volume relative to the whole of the resin compositionwas also expressed in each of the parentheses. Also, the followingmaterials were used as the respective components in Tables 2 and 3.

(E) Thermosetting Resin:

E-1: Phenol novolak type epoxy resin [EPICLON N-770, manufactured by DICCorporation]E-2: Bisphenol A novolak type epoxy resin [EPICLON N-865, manufacturedby DIC Corporation]E-3: Biphenyl aralkyl type epoxy resin [NC-3000, manufactured by NipponKayaku Co., Ltd.]Curing agent: Cresol novolak type phenol resin [PHENOLITE KA-1165,manufactured by DIC Corporation]Curing accelerator: 2-Ethyl-4-methylimidazole [CUREZOL2E4MZ,manufactured by Shikoku Chemicals Corporation]

(F) Silica:

F-1: Fused spherical silica slurry [SC2050-KC, manufactured by AdmatechsCompany Limited, average particle size: 0.5 μm, solid content: 70% bymass]F-2: Fused spherical silica slurry [SC4050-KNA, manufactured byAdmatechs Company Limited, average particle size: 1.0 μm, solid content:70% by mass]

(G) Molybdenum Compound:

G-1: Zinc molybdate [a reagent, manufactured by Strem Chemicals Inc.,average particle size: 2 μm]G-2: Zinc molybdate-supported talc [KEMIGARD 911C, manufactured bySherwin-Williams Company, average particle size: 3 μm]G-3: Calcium molybdate [a reagent, manufactured by Strem Chemicals Inc.,average particle size: 2 μm]G-4: Magnesium molybdate [a reagent, manufactured by Mitsuwa ChemicalsCo., Ltd., average particle size: 3 μm]Inorganic filler 1: Burnt talc [BST, manufactured by Nippon Talc Co.,Ltd.]Inorganic filler 2: Molybdenum disulfide [A Powder, manufactured byNichimoly Division, Daizo Corporation]Inorganic filler 3: Aluminum hydroxide [C-303, manufactured by SumitomoChemical Co., Ltd.]Organic solvent: Cyclohexanone [manufactured by Godo Co., Ltd.]

Each of the copper clad laminate plates obtained in the foregoingExamples and Comparative Examples was measured and evaluated withrespect to characteristics by the following methods. The measurement andevaluation results are shown in Tables 4 and 5.

(1) Evaluation of Drilling Processability:

Two sheets of a copper clad laminate plate having a thickness of 0.4 mmwere superimposed; a paper phenol board having a thickness of 0.4 mm wasdisposed thereabove, whereas a paper phenol board having a thickness of1.5 mm was disposed thereunder; 6,000 holes were drilled with a drillhaving a diameter of 0.2 mm by using a drilling machine [ND-1V212,manufactured by Hitachi Via Mechanics, Ltd.] under a condition at arotation number of 160 krpm and a feed rate of 1.8 m/min under a chipload of 11.25 μm/rev; and a wear amount of drill cutting blade and holeregistration accuracy were measured by the following methods, therebyevaluating the drilling processability.

(a) Wear Amount of Drill Cutting Blade:

A drilling cutting blade portion of a new product (before drilling) andafter drilling was observed from the drill central axis by using ascanning electron microscope [S-4700, manufactured by Hitachi, Ltd.],and a wear retreat amount of cutting blade edge was measured and definedas the wear amount of drill cutting blade.

(b) Hole Registration Accuracy:

Of the two-ply copper clad laminate plates, a registration deviationamount of holes of the lower side (drill exit side) of the second sheetwas measured using a hole registration accuracy analyzer [HT-1AM,manufactured by Hitachi Via Mechanics, Ltd.], and average +3σ (σ:standard deviation) of registration deviation amounts of the 4,001st to6,000th hit holes was calculated and defined as the hole registrationaccuracy. So far as the hole registration accuracy is not more than 35μm, favorable results are revealed without causing a problem in view ofthe practical use.

(2) Measurement of Coefficient of Thermal Expansion:

After removing a copper foil of a copper clad laminate plate having athickness of 0.8 mm with an etching liquid, the resulting laminate platewas cut into a size of 5 mm square, thereby fabricating a specimen. Anaverage coefficient of linear thermal expansion of this specimen in themachine direction (longitudinal direction of the glass cloth) at from50° C. to 120° C. was measured at a temperature rising rate of 10°C./rain by using a TMA test apparatus [TMA2940, manufactured by TAInstruments]. The closer the coefficient of thermal expansion to acoefficient of thermal expansion of a silicon chip (from 4×10⁻⁶/° C. to5×10⁻⁶/° C.), the more favorable the results are.

(3) Measurement of Electrical Insulating Properties:

After removing a copper foil on one surface of a copper clad laminateplate having a thickness of 0.1 mm with an etching liquid while leavinga circular portion having a diameter of 20 mm, the resulting laminateplate was cut into a size of 50 mm square such that the circular portionwas located in the center, thereby fabricating a specimen. This specimenwas dipped in FLUORINERT [manufactured by Sumitomo 3M Limited] andsubjected to a dielectric breakdown test under a condition at a pressurerising rate of 5 kV/10 sec. by using a withstanding voltage meter[PT-1011, manufactured by TOA Electronics Ltd.], thereby measuring adielectric breakdown voltage. So far as the dielectric breakdown voltageis 6 kV or more, favorable results are revealed without causing aproblem in view of the practical use.

(4) Evaluation of Moldability:

A copper clad laminate plate having a thickness of 0.4 mm was cut into asize of 5 mm square and cast with a casting resin, and the cut surfacewas polished to fabricate a specimen for cross section observation. Thepolished surface of this specimen was subjected to milling by a flatmilling apparatus [E-3200, manufactured by Hitachi, Ltd.] and thenobserved by using a scanning electron microscope [S-4700, manufacturedby Hitachi, Ltd.] to examine the presence or absence of a void, therebyevaluating the moldability.

TABLE 4 Item Unit Example 4 Example 5 Example 6 Example 7 Drilling Wearamount of μm 11 8 9 10 processability drill cutting blade Holeregistration μm 34 31 30 31 accuracy Coefficient of thermal expansion10⁻⁶/° C. 10.8 13.1 11.3 13.1 Electrical insulating properties kV 6.97.7 7.1 8.0 Moldability (presence or absence — Absent Absent AbsentAbsent of void)

TABLE 5 Comparative Comparative Comparative Comparative Item UnitExample 4 Example 5 Example 6 Example 7 Drilling Wear amount of μm 18 728 13 processability drill cutting blade Hole registration μm 42 31 5038 accuracy Coefficient of thermal expansion 10⁻⁶/° C. 10.3 14.9 11.313.2 Electrical insulating properties kV 3.5 7.6 7.1 2.6 Moldability(presence or absence — Present Absent Absent Absent of void)

As is clear from Table 4, all of the Examples of the present inventionare excellent in the drilling processability and low thermal expansionproperties and are of no problem in the electrical insulating propertiesand moldability.

On the other hand, as is clear from Table 5, in Comparative Example 4,since the content of silica exceeds 60% by volume of the whole of theresin composition, the moldability is significantly inferior and loweredin the drilling processability and electrical insulating properties. InComparative Example 5, since the content of silica is less than 20% byvolume of the whole of the resin composition, there is such a problemthat the coefficient of thermal expansion is large. In ComparativeExample 6, since the molybdenum compound of the present invention is notcontained, the drilling processability is significantly inferior.Similarly, in Comparative Example 7, since the molybdenum compound ofthe present invention is not contained, and molybdenum disulfide iscontained, the electrical insulating properties are significantlyinferior.

Examples 8 and 9 and Comparative Examples 8 and 9

In blends of resin composition varnishes shown in Table 6, first of all,(I) a molybdenum compound was gradually added to (H) a silica slurry andmixed while stirring such that an aggregated block was not formed. Thissilica slurry having the molybdenum compound mixed therewith was treatedthree times under a condition at an air pressure of 0.5 MPa by using ananomizer (NM2000-AR, manufactured by Yoshida Kikai Co., Ltd.), therebythoroughly dispersing and mixing the molybdenum compound and the silicaparticles.

Subsequently, this molybdenum compound-dispersed silica slurry wasgradually added to a resin varnish which had been prepared by dissolving(J) a thermosetting resin and a curing agent in an organic solvent,while stirring, and after the whole amount was completely added, thecomponents were stirred for one hour until the whole became homogenous.

Thereafter, (K) an inorganic filler slurry was added to the resinvarnish while stirring, to which was then further added a curingaccelerator, and the components were stirred for one hour until thewhole became homogenous, thereby preparing a resin composition varnish.

A solid content concentration of each of the resin composition varnishesof Examples 8 and 9 and Comparative Examples 8 and 9 was 70% by mass.

Comparative Example 10

In a blend of a resin composition varnish shown in Table 6, (I) amolybdenum compound was gradually added to a resin varnish which hadbeen prepared by dissolving (J) a thermosetting resin and a curing agentin an organic solvent, while stirring, and after the whole amount wascompletely added, the components were stirred for one hour until thewhole became homogenous.

Thereafter, (K) an inorganic filler slurry was added to the resinvarnish while stirring, to which was then further added a curingaccelerator, and the components were stirred for one hour until thewhole became homogenous, thereby preparing a resin composition varnish.

A solid content concentration of the resin composition varnishes ofComparative Example 10 was 70% by mass.

Comparative Example 11

In a blend of a resin composition varnish shown in Table 6, first ofall, (I) a molybdenum compound was gradually added to (H) a silicaslurry and mixed while stirring such that an aggregated block was notformed. This silica slurry having the molybdenum compound mixedtherewith was treated three times under a condition at an air pressureof 0.5 MPa by using a nanomizer (NM2000-AR, manufactured by YoshidaKikai Co., Ltd.), thereby thoroughly dispersing and mixing themolybdenum compound and the silica particles.

Subsequently, this molybdenum compound-dispersed silica slurry wasgradually added to a slurry of (K) an inorganic filler while stirring,and after the whole amount was completely added, the components werestirred for one hour until the whole became homogenous.

Thereafter, this slurry was added to a resin varnish which had beenprepared by dissolving (J) a thermosetting resin and a curing agent inan organic solvent, while stirring, to which was then further added acuring accelerator, and the components were stirred for one hour untilthe whole became homogenous, thereby preparing a resin compositionvarnish.

A solid content concentration of the resin composition varnishes ofComparative Example 11 was 70% by mass.

Each of the resin composition varnishes manufactured in the foregoingExamples and Comparative Examples was impregnated and coated on anE-glass cloth (WEA116E, manufactured by Nitto Boseki Co., Ltd.) having athickness of 0.1 mm, followed by heating for drying at 160° C. for 5minutes, thereby obtaining a prepreg having a content of the resincomposition of 48% by mass. Four sheets of this prepreg weresuperimposed, and an electrolytic copper foil having a thickness of 12μm was disposed on the top and bottom, followed by vacuum pressing undera pressure of 3.8 MPa at a temperature of 185° C. for 90 minutes,thereby obtaining a copper clad laminate plate.

By using the thus obtained resin composition varnish and copper cladlaminate plate, precipitation properties of the resin compositionvarnish, the presence or absence of an aggregate in the varnish,drilling processability of the copper clad laminate plate, and acoefficient of thermal expansion were measured and evaluated by thefollowing methods. The evaluation results are summarized in Table 7.

(1) Evaluation of Precipitation Properties of Resin Composition Varnish:

500 cm³ of the resin composition varnish was taken in a glass-madesettling tube having a diameter of 5 cm and a length of 35 cm andallowed to stand at room temperature of 25° C., and a time until aprecipitate accumulated on the bottom of the settling tube was measured,thereby evaluating the precipitation properties.

(2) Evaluation of Presence or Absence of Aggregate in Resin CompositionVarnish:

100 cm³ of the resin composition varnish was taken in a flask, to whichwas then added 400 cm³ of an organic solvent the same as that used inthe varnish, and the mixture was well shaken. This dilute varnish wasfiltered through a nylon mesh having an opening of 20 μm, and whether ornot a residue remained on the mesh was visually confirmed, therebyevaluating the presence or absence of an aggregate.

(3) Evaluation of Drilling Processability of Copper Clad Laminate Plate:

Two sheets of a copper clad laminate plate were superimposed; analuminum foil having a thickness of 0.15 mm was disposed thereabove,whereas a paper phenol board having a thickness of 1.5 mm was disposedthereunder; 6,000 holes were drilled with a drill φ0.2 mm by using adrilling machine [ND-1V212, manufactured by Hitachi Via Mechanics, Ltd.]under a condition at a rotation number of 160 krpm and a feed rate of 2m/min under a chip load of 12.5 μm/rev; and a wear amount of drillcutting blade and hole registration accuracy were measured by thefollowing methods, thereby evaluating the drilling processability.

(a) Wear Amount of Drill Cutting Blade:

A drilling cutting blade portion before and after drilling was observedfrom the drill central axis by using a scanning electron microscope(S-4700, manufactured by Hitachi, Ltd.), and a wear retreat amount ofcutting blade edge was measured and defined as the wear amount of drillcutting blade.

(b) Hole Registration Accuracy:

Of the two-ply copper clad laminate plates, a registration deviationamount of holes of the lower side (drill exit side) of the second sheetwas measured using a hole registration accuracy analyzer (HT-1AM,manufactured by Hitachi Via Mechanics, Ltd.), and average +3σ (σ:standard deviation) of registration deviation amounts of the 4,001st to6,000th hit holes was calculated and defined as the hole registrationaccuracy.

(4) Measurement of Coefficient of Thermal Expansion of Copper CladLaminate Plate:

After removing a copper foil of a copper clad laminate plate with anetching liquid, the resulting laminate plate was cut into a size of 5 mmsquare, thereby fabricating a specimen. A coefficient of thermalexpansion of this specimen in the machine direction (longitudinaldirection of the glass cloth) at from 50° C. to 120° C. was measured ata temperature rising rate of 10° C./min by using a TMA test apparatus(TMA2940, manufactured by TA Instruments).

TABLE 6 Comparative Comparative Comparative Comparative ComponentExample 8 Example 9 Example 8 Example 9 Example 10 Example 11 (H) Slurryhaving H-1 20 20 silica particle H-2 30 dispersed in H-3 12 organicsolvent H-4 60 (I) Molybdenum I-1 23.4 23.4 23.4 23.4 compound I-2 23.9I-3 19.0 (J) Thermosetting resin 100 100 100 100 100 100 Curing agent 6363 63 63 63 63 Curing accelerator 1 1 1 1 1 1 Organic solvent 69 59 7729 79 69 (K) Inorganic filler 402 (47) 402 (47) 402 (47) 402 (47) 406(47.5) 402 (47) Unit: Parts by mass (however, % by volume in theparenthesis)

Table 6 shows a blend regarding the resin composition varnishmanufactured by the manufacturing method of each of the Examples andComparative Examples, as expressed in terms of parts by mass in the casewhere the blending amount of the thermosetting resin (J) is defined as100 parts by mass. However, with respect to each of the slurry havingthe silica particle (H) dispersed in an organic solvent and theinorganic filler (K), the blending amount including the organic solventcontained therein is shown. Of these, with respect to (K), a value of %by volume of the inorganic filler in the case where the whole of theresin composition exclusive of the organic solvent contained in theresin composition varnish is defined 100% by volume was also expressedin each of the parentheses. Also, with respect to the molybdenumcompound (I), in the case of using a particle in which the molybdenumcompound is supported by other substance, a blending amount as thesupported particle but not the molybdenum compound alone is shown.

Also, the following materials were used as the respective components inTable 6.

(H) Silica slurry H-1: Slurry in which silica having an average particlesize of 0.05 μm and a specific surface area of 55 m²/g is dispersed in asilica blending amount of 30% by mass in propylene glycol monomethylether (ADMANANO, manufactured by

Admatechs Company Limited)

(H) Silica slurry H-2: Slurry in which silica having an average particlesize of 0.025 μm and a specific surface area of 110 m²/g is dispersed ina silica blending amount of 20% by mass in propylene glycol monomethylether (ADMANANO, manufactured by Admatechs Company Limited)(H) Silica slurry H-3: Slurry in which silica (SO-25R, manufactured byAdmatechs Company Limited) having an average particle size of 0.5 μm anda specific surface area of 7 m²/g is dispersed in a silica blendingamount of 50% by mass in propylene glycol monomethyl ether(H) Silica slurry H-4: Slurry in which silica (380, manufactured byNippon Aerosil Co., Ltd.) having an average particle size of 0.05 μm anda specific surface area of 380 m²/g is dispersed in a silica blendingamount of 10% by mass in propylene glycol monomethyl ether(I) Molybdenum compound I-1: Zinc molybdate (a reagent, manufactured byStrem Chemicals Inc.)(I) Molybdenum compound I-2: Calcium molybdate (a reagent, manufacturedby Strem Chemicals Inc.)(I) Molybdenum compound I-3: Zinc molybdate-supported talc, zincmolybdate content: 10% by mass (KEMIGARD 911C, manufactured bySherwin-Williams Company)(J) Thermosetting resin: Phenol novolak type epoxy resin (EPICLON N-770,manufactured by DIC Corporation)Curing agent: Cresol novolak type phenol resin (PHENOLITE KA-1165,manufactured by DIC Corporation)Curing accelerator: 2-Ethyl-4-methyl imidazole [(2E4MI, manufactured byShikoku Chemicals Corporation)Organic solvent: Propylene glycol monomethyl ether (manufacture by GodoCo., Ltd.)(K) Inorganic filler: Fused spherical silica slurry, average particlesize: 0.5 μm, specific surface area: 7 m²/g, silica blending amount: 70%by mass (SC2050-KC, manufactured by Admatechs Company Limited)

TABLE 7 Example Example Comparative Comparative Comparative ComparativeItem Unit 8 9 Example 8 Example 9 Example 10 Example 11 Precipitationproperties h 72 84 12 84 48 72 Aggregate — No No No Yes Yes Yes DrillingWear amount of μm 10 9 12 10 12 10 processabiiity drill cutting bladeHole registration μm 30 31 30 34 35 31 accuracy Coefficient of thermalexpansion 10⁻⁶/° C. 11.5 11.7 11.4 12.0 11.3 11.5

As is clear from Table 7, the Examples of the present invention areexcellent in all of the issues regarding the precipitation propertiesand presence or absence of an aggregate of the resin compositionvarnish, and the drilling processability and coefficient of thermalexpansion of the copper clad laminate plate.

On the other hand, in Comparative Example 8, since the silica particlein the slurry (H) is large in the average particle size and small in thespecific surface area, the precipitation properties of the resincomposition varnish are significantly inferior.

Also, in Comparative Example 9, since the silica particle in the slurry(H) is large in the specific surface area, the aggregate remains in theresin composition varnish, and the hole registration accuracy isslightly deteriorated. In Comparative Example 10, since the molybdenumcompound-supported talc is added directly to the resin varnish, theprecipitation properties of the resin composition varnish are inferior,and the aggregate remains. Furthermore, the hole registration accuracyis slightly deteriorated. In Comparative Example 11, since themolybdenum compound-dispersed silica slurry is added to the inorganicfiller slurry and then added to the resin varnish, the aggregate remainsin the resin composition varnish.

Incidentally, if a printed wiring board is fabricated in a state inwhich the aggregate remains in the resin composition varnish, there is aconcern that abnormal deposition of a plating to be caused due tomolybdenum, or the like is easily generated during the manufacture,thereby impairing the reliability as an electronic appliance, andtherefore, such is not preferable.

In the light of the above, according to the present invention, a resincomposition varnish in which the precipitation or aggregation of amolybdenum compound hardly occurs can be manufactured, and by usingthis, a prepreg and a laminate plate, each of which has a lowcoefficient of thermal expansion and high drilling processability andwhich is suitable for semi-conductor packages or printed wiring boards,can be obtained.

INDUSTRIAL APPLICABILITY

The thermosetting resin composition of the present invention isespecially low in thermal expansion properties and excellent in drillingprocessability and heat resistance, and it is suitably used forelectronic components, etc. Also, according to the laminate plate forwiring boards of the present invention, it is possible to provide alaminate plate for wiring boards, which is very excellent in drillingprocessability at the time of fabricating a wiring board and which alsohas favorable electrical insulating properties and low thermal expansionproperties. Furthermore, according to the varnish obtained by the methodfor manufacturing a resin composition varnish of the present invention,it is possible to provide a prepreg and a laminate plate each havinghigh drilling processability.

1. A thermosetting resin composition comprising (A) a maleimide compoundcontaining an unsaturated maleimide compound having an acidicsubstituent, as represented by the following general formula (I) or(II), (B) a thermosetting resin, (C) an inorganic filler, and (D) amolybdenum compound:

wherein R₁ represents a hydroxyl group, a carboxyl group, or a sulfonicacid group, each of which is the acidic substituent; each of R₂, R₃, R₄,and R₅ independently represents a hydrogen atom, an aliphatichydrocarbon group having a carbon number of from 1 to 5, or a halogenatom; A represents an alkylene group, an alkylidene group, an ethergroup, a sulfonyl group, or a group represented by the following formula(III); x represents an integer of from 1 to 5; y represents an integerof from 0 to 4; and a sum of x and y is 5:


2. The thermosetting resin composition according to claim 1, wherein themolybdenum compound (D) is at least one member selected from the groupconsisting of a molybdenum oxide and a molybdic acid compound, and acontent of the molybdenum compound is from 0.02 to 20% by volume of thewhole of the resin composition.
 3. The thermosetting resin compositionaccording to claim 1, wherein the thermosetting resin (B) is an epoxyresin; a total sum content of the component (A) and the component (B) isfrom 30 to 80% by volume of the whole of the resin composition; and amass ratio of the component (A) and the component (B) is from 20 to 90parts by mass in terms of the component (A) based on 100 parts by massof the total sum content of the component (A) and the component (B). 4.The thermosetting resin composition according to claim 1, wherein theinorganic filler (C) is fused spherical silica, and a content of theinorganic filler is from 10 to 60% by volume of the whole of the resincomposition.
 5. A prepreg obtained by impregnating or coating a basematerial with the thermosetting resin composition according to claim 1and then performing B-staging.
 6. A laminate plate obtained bylaminating and molding the prepreg according to claim
 5. 7. The laminateplate according to claim 6, which is a metal clad laminate plateobtained by superimposing a metal foil on at least one surface of theprepreg and then performing heat pressure molding.
 8. A laminate platefor wiring boards, obtained by coating a thermosetting resin compositioncontaining (E) a thermosetting resin, (F) silica, and (G) at least onemolybdenum compound selected from the group consisting of zincmolybdate, calcium molybdate, and magnesium molybdate, with a content ofthe silica (F) being 20% by volume or more and not more than 60% byvolume, on a base material in a film form or fiber form, then performingsemi-curing to form a prepreg, and laminating and molding the prepreg.9. The laminate plate for wiring boards according to claim 8, whereinthe silica (F) is fused spherical silica having an average particle sizeof 0.1 μm or more and not more than 1 μm, and a content of themolybdenum compound (G) is from 0.1% by volume or more and not more than10% by volume of the whole of the resin composition.
 10. The laminateplate for wiring boards according to claim 8, wherein the thermosettingresin composition is varnished.
 11. The laminate plate for wiring boardsaccording to claim 8, wherein the base material in a film form or fiberform is a glass cloth.
 12. A method for manufacturing a resincomposition varnish comprising a first dispersing and mixing step ofdispersing and mixing (I) a molybdenum compound in (H) a slurrycontaining a silica particle having an average particle size of 0.01 μmor more and not more than 0.1 μm and a specific surface area of 30 m²/gor more and not more than 270 m²/g, a second dispersing and mixing stepof dispersing and mixing the slurry having gone through the firstdispersing and mixing step in a varnish containing (J) a thermosettingresin, and a third dispersing and mixing step of dispersing and mixing(K) an inorganic filler exclusive of the silica particle and themolybdenum compound in the varnish having gone through the seconddispersing and mixing step.
 13. The method for manufacturing a resincomposition varnish according to claim 12, further comprising a curingaccelerator adding step of adding a curing accelerator to the varnishafter the third dispersing and mixing step.
 14. The method formanufacturing a resin composition varnish according to claim 12, whereinthe molybdenum compound (I) is one member or a mixture of two or moremembers selected from the group consisting of zinc molybdate, calciummolybdate, and magnesium molybdate.
 15. A prepreg comprising a basematerial impregnated and coated with a resin composition obtainedthrough a first dispersing and mixing step of dispersing and mixing (I)a molybdenum compound in (H) a slurry containing a silica particlehaving an average particle size of 0.01 μm or more and not more than 0.1μm and a specific surface area of 30 m²/g or more and not more than 270m²/g; a second dispersing and mixing step of dispersing and mixing theslurry having gone through the first dispersing and mixing step in avarnish containing (J) a thermosetting resin; and a third dispersing andmixing step of dispersing and mixing (K) an inorganic filler in thevarnish having gone through the second dispersing and mixing step.
 16. Alaminate plate obtained by laminating and molding the prepreg accordingto claim 15.